/* Copyright (C) 2000 MySQL AB

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/*
  Radixsort for pointers to fixed length strings.
  A very quick sort for not to long (< 20 char) strings.
  Neads a extra buffers of number_of_elements pointers but is
  2-3 times faster than quicksort
*/

#include "mysys_priv.h"
#include <m_string.h>

/* Radixsort */

void radixsort_for_str_ptr(uchar **base, uint number_of_elements, size_s size_of_element, uchar **buffer)
{
  uchar **end, **ptr, **buffer_ptr;
  uint32 *count_ptr, *count_end, count[256];
  int pass;

  end = base + number_of_elements;
  count_end = count + 256;
  for (pass = (int)size_of_element - 1; pass >= 0; pass--)
  {
    bzero((gptr)count, sizeof(uint32) * 256);
    for (ptr = base; ptr < end; ptr++) count[ptr[0][pass]]++;
    if (count[0] == number_of_elements)
      goto next;
    for (count_ptr = count + 1; count_ptr < count_end; count_ptr++)
    {
      if (*count_ptr == number_of_elements)
        goto next;
      (*count_ptr) += *(count_ptr - 1);
    }
    for (ptr = end; ptr-- != base;) buffer[--count[ptr[0][pass]]] = *ptr;
    for (ptr = base, buffer_ptr = buffer; ptr < end;) (*ptr++) = *buffer_ptr++;
  next:;
  }
}
